A computer network typically comprises a plurality of interconnected entities that transmit (i.e., "source") or receive (i.e., "sink") messages, such as frames or packets. A common type of computer network is a local area network ("LAN") which typically refers to a privately owned network within a single building or campus. LANs employ a data communication protocol (LAN standard), such as Token Ring, Ethernet or Token Bus, that defines the functions performed by the data link and physical layers of a communications architecture (i.e., a protocol stack), such as the Open Systems Interconnection (OSI) Reference Model from the International Standards Organization.
To form a wide area network ("WAN"), metropolitan area network ("MAN") or intranet, one or more intermediate devices are often used to couple multiple LANs together. For example, a bridge may be used to provide a "bridging" function between two or more LANs. Alternatively, a switch may be utilized to provide a "switching" function for transferring information, such as data frames, between LANs. Typically, the switch is a computer having a plurality of ports that couple the switch to several LANs and to other switches. The switching function includes receiving data frames at a source port and transferring them to at least one destination port.